The present invention relates to a method for the control of a brake slip control apparatus, in particular for automotive vehicles, wherein the rotational behavior of the wheels and/or of the axles is sensed with the aid of sensors and the sensor signals for the generation of valve control signals are processed electronically, these valve control signals serving to govern the braking pressure at the wheels dependent upon the wheel rotational behavior.
Methods and circuits of this type are basically subject to the requirement for high reliability of service and dependability. False reactions would in any case be very dangerous because the operation of brake slip control apparatuses is principally based on the temporary reduction of braking pressure to prevent a wheel lock, and thus, as it is meant to do, puts the brake unit at the individual vehicle wheels out of operation for a short time.
To prevent dangerous driving conditions and to reduce the risks imminent due to errors in the brake slip control apparatus, the brake slip control apparatus has to be disconnected upon the occurrence of interferences or defects, to the end that at least braking of the vehicle without slip control remains possible.
It is already known to additionally fit safety circuits and monitoring circuits into the control apparatus which upon interference will disconnect the entire anti-locking control system (German Patent DE-OS No. 2,340,575), or to integrate the safety circuits into the control circuits for the individual wheels (German Patent DE-AS No. 2,534,904) such that only the respective defect control circuit will be disconnected. By insertion of the monitoring circuit assigned to a wheel into the control circuit of another wheel, it is desired in the last-mentioned case (German Patent DE-AS No. 2,534,904) to reduce the number of electronic components required and to achieve furthermore that, even in the event of complete failure of a control circuit chip, the error will be indicated, namely, through the safety circuit in the intact control circuit chip.
It is furthermore known to insert into a brake slip regulator, which is equipped with at least one microcomputer for the slip control, another microcomputer for the checking and monitoring of the control channels, with the test computer including a device for the generation and the storage of test signals as well as a self-testing device. The test computer is connected to several warning devices and includes a control unit which after the start of braking interrupts the checking of the control signals and the activation of the self-testing device (German Patent DE-OS No. 2,928,981).
There is finally also known an electronic anti-locking regulator for automotive vehicles, wherein assigned to each controlled wheel is an individual channel with a calculating circuit and with a test circuit identical with the calculating circuit, and wherein the output signals of the calculating circuits and of the test circuits of different channels are in each case constantly compared in pairs with respect to equivalence or non-equivalence. The outputs of the comparators are in turn interconnected in a like manner until only two outputs having an equidirectional alternating signal are supplied to a last comparator, the output signal enables the recognition of an error in a calculating circuit or in a test circuit (German Patent DE-OS No. 2,612,356, U.S. Pat. No. 4,113,321).